JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS Vol. 20, No. 9-10, September – October 2018, p. 537 - 542 Characterization and optical properties of 1,5-diphenylcarbazide sensor thin film for sensing application Y. W. FENa,b,*, A. A. ZAINUDINa, N. E. SAFIEa, W. M. M. YUNUSa, Z. A. TALIBa, N. A. YUSOFc, N. A. S. OMARb, W. M. E. M. M. DANIYALb, S. SALEVITERb aDepartment of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Malaysia bFunctional Devices Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Malaysia cDepartment of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Malaysia Optical properties of 1,5-diphenylcarbazide sensor thin film have been investigated. In this project, The 1,5- diphenylcarbazide solution was prepared by dissolving powder form of 1,5-diphenylcarbazide with three types of solvent which were acetone, acetic acid and ethanol with 0.08 mol L-1 molar concentration. It was then deposited on glass cover slip (substrate) using spin coating technique. The obtained thin film was confirmed and characterized by FTIR and AFM while the optical properties were evaluated by UV-VIS NIR spectroscopy. From the absorption edge studies, the values of the absorption coefficient and optical band gap have been found to be varies from 3.97 eV to 4.09 eV. From the experimental results, values of optical band gap are calculated and found to be dependent on the molar concentration of solution and type of solvents used. (Received September 22, 2017; accepted October 10, 2018) Keywords: Thin film, Optical, 1,5-Diphenylcarbazide, Sensing 1. Introduction 1,5-diphenylcarbazide (C13H14N4O) has melting point in between of 173 – 176 degree Celcius and it have 1,5-diphenylcarbazide has been used as a reagent in molecular weight of 242.28 gram per mole. The physical the laboratory for many research areas especially in state is in solid form and usually appears in white or pink electrochemical studies, molecular studies and many more. and odorless powder. Pure C13H14N4O is stable and Despite of the instrumental improvements of the last sensitive to the light. It can be easily soluble in hot decades, the colorimetric techniques are still attractive alcohol, acetone, ethanol and glacial acetic acid. from an analytical point of view since they are cheap, Furthermore, it is incompatible with oxidizing agent sensitive and easy to implement in routine laboratories [1]. because it can be easily oxidized to diphenylcarbazone. In the other hand, Pflaum and Howick state that in the However, through several decades later many questions field of trace metal determinations, a plethora of organic regarding the mechanism of these reactions remain colorimetric reagents are still widely employed [2]. One of unexplained. The mechanism of oxidation of 1,5- organic colorimetric reagents that deserves a special diphenylcarbazide into diphenylcarbazone was recently attention is 1,5-diphenylcarbazide, which is commonly studied by using electrochemical and spectrochemical used in determination of trace metal. techniques by Balt and Van Dalen in the year 1962 [3,4]. However, no confirmation of the possible intermediates was given probably due to the similarity between both of their properties. 1,5-diphenylcarbazide also can be considered as an importance substance to detect heavy metal ion especially in environmental pollution. Research done by Jaya and Ramakrishnan in the year 1982 had used 1,5-diphenylcarbazide to determine osmium using spectrophotometric method [5]. Research on thin film started in the 17th century but it seemed to be simply based on curiosity. In the 19th century, the scientific research is thought to have begun. Thin film is widely spread in development of optics, th Fig 1. Molecular structure of 1,5-diphenylcarbazide electronics and electron spectroscopy in the 20 century. (C13H14N4O). Nowadays, the results of researches play the most important rules in advanced technology where thin films 538 Y. W. Fen, A. A. Zainudin, N. E. Safie, W. M. M. Yunus, Z. A. Talib, N. A. Yusof, N. A. S. Omar … are one of the most important tools for the preparation of absorption centered near the wavelength of the major novel materials. transition. Sensors in a thin film form provide a minimally The application of 1,5-diphenylcarbazide for the importunate means of measuring surface parameters, such analytic determination of metal species such as chromium, as strain or temperature in inimical environments. They copper and mercury were firstly reported by Cazaneuve in are needed in engine system to evaluate advanced the year 1900 [15]. By far, the reaction with chromium is materials and components and to provide experimental received more attention since it has high sensitivity and verification of computational models. Some of the relevant selectivity. However, there is no work reported to link the characteristics of sensors are flexibility and elastically. relationship of optical properties of 1,5-diphenylcarbazide They can be configurated as single sensors or arranged in a in determining the metal species. It is of interest to study matrix to fit different measuring surfaces. By selecting the optical properties of 1,5-diphenylcarbazide thin film proper material and design will give novel sensors the with solvents used which are acetic acid, acetone and ability to conform around highly contoured sites without ethanol. wrinkling. An assortment of coatings can be applied to novel sensors. The important of optical properties are absorption, 2. Experimental refractive index, dispersion and transmission. Usually these properties are classified by the chemical composition 2.1. Chemical preparation and by melting process to a lesser degree and the subsequent thermal treatment. Basically, optics brings a lot 1,5-diphenylcarbazide with 242.85 g/mol molecular of benefit into human life either in the field of technology weight was purchased from BDH Chemicals LTD (Poole, or even in science field [6]. England). The powder form of 1,5-diphenylcarbazide is For optical materials in imaging or non-imaging dissolved with three types of solvent which are glacial optical system detailed knowledge of the wavelength acetic acid (R&M Marketing, Essex, UK), absolute dependent complex index of refraction is important for ethanol (HmbG Chemicals, IL, USA) and acetone (HmbG optical system design and performance. The optical Chemicals, IL, USA). The process has been carried out in absorption of UV light by the materials can contribute to room temperature. 1.0 g of 1,5-diphenylcarbazide have optical degradation of the materials and reduced been prepared and dissolved it in 50 ml solvent. It was performance over time [7]. dissolved in glacial acetic acid, acetone and ethanol The optical properties of polymer are widely spread in solution. The solution was stirred until 1,5- the research area recently [8-12]. For instance, in the year diphenylcarbazide dissolved. The solution is transferred 2009, Samuels et al. had studied the optical properties of into 50 ml volumetric flask until reach the mark point of various fluoropolymers, hydrocarbon polymers, and volumetric flask. polyimides. It is useful for concentrator photovoltaic (CPV) system design of the geometrical optics and also provides insights into the system’s optical absorption. 2.2. Preparation of films When a light passes through compound, the molecules will absorb the light energy. Eventually, an electron is The glass cover slips were cleaned using acetone to promoted from an occupied orbital to an unoccupied clean off the dirt on the surface of glass laid. Then they orbital. The transition that results from the absorption of were deposited with the analytical solution using spin light is known as the transition between electronic energy process controller (Spin-3000 A, Midas System). Spin levels. The energy differences between electronic levels in coating technique was used to produce a thin layer on the most molecules vary from 125 to 650 kJ/mole [13]. top of the glass [16,17]. Approximately 1 µl of the The absorption spectrum for an atom that absorb in solution was placed on the glass slip. The glass cover slip ultraviolet sometimes consists of very sharp lines, as was spun at 4000 rev/min for 60 second using spin coating would be expected for a quantized process occurring system [18-20]. After that, the glass cover slip was between two discrete energy levels. The energy level allowed to dry at room temperature for 3 minutes. diagram of isolated atoms consists with discrete energies. The optical transition between these level give rise to sharp lines in the absorption and emission spectra [13]. 2.3. Characterization of sample However for molecules, the ultraviolet absorption usually occurs over a wide range of wavelengths because Morphological features and surface characteristics of there are many states of vibrational and rotational sample were obtained from scanning electron microscopy excitation. The rotational and vibrational levels are thus, (SEM) using JEOL JSM-6400 microscope (Tokyo, Japan). superimposed on the electronic levels and give a UV-VIS NIR spectrophotometer (UV-3600) from combination of overlapping lines. This appears as a Shimadzu (Kyoto, Japan) was used to determine the continuous absorption band. A molecule may therefore absorbance of samples in the range of 200-900 nm. undergo electronic and and vibrational-rotational Accordingly, the predetermined electromagnetic radiation excitation simultaneously [14]. Hence, it can be observed wavelengths for ultra-violet (UV) is between 300-400 nm, that a molecule usually consists of a broad band of visible (VIS) is 400 to 765 nm and near infra-red (NIR) Characterization and optical properties of 1,5-diphenylcarbazide sensor thin film for sensing application 539 are defined as 765 to 3200 nm. The Fourier transform spectroscopy (FTIR) spectra of the sample ranging from 400-4000 cm-1 were obtained on a Perkin-Elmer spectrophotometer (CA, USA). 3. Result and discussion 3.1. Fourier transform infrared spectroscopy (FTIR) spectra The Infrared spectrum is basically a plot of transmitted frequencies against intensity of the transmission.